Fuse



July 31, 1934. c'. H. GUNTHORP FUSE Filed May 25, 1932 JnUeTiZFfT: C661]H Gard/10779- B Patented July 31, 1934 UlTED srrss PATENT OFFICE FUSE VI Cecil H. Gunthorp, Des Plaines, 111., assignor to Economy Fuse andManufacturing (30., Chicago, 111., a corporation of New York ApplicationMay 23, 1932, Serial No. 612,932

17 Claims.

The present invention relates to electrical fuses and the like.

Among the objects of the present invention is to provide a novel fuse ofrelatively simple construction having few parts adapted to be easilyassembled.

Another object of the present invention is to provide a novel fuse ofthe type used in electrical circuits for homes, ofiice buildings and thelike,

in which a fusible element is inserted in an electrical circuit which isadapted to melt or burn to prevent damage to electrical equipment when ashort circuit or overload occurs in the line or circuit.

In a fuse of the type herein referred to wherein the fusible element isenclosed within a chamber and visible through an opening provided in oneof the elements of the fuse, it is very essential to provide aconstruction in which the arc, produced at the time of the short circuitin the line,

is extinguished before the same has had an opportunity to travel beyondthe confines of the fuse in order to prevent fire hazards which wouldotherwise be present. It is also important to provide a construction inwhich the pressure of the gases formed as a result of the combustion ofthe fusible element at the time this short circuit occurs may build upto a point sufficient to extinguish the arc, but less than would berequired to cause a bursting of the fuse. It is also essential toprovide a fuse construction in which these hot gases resulting from themelting or combustion of the fusible element will be confined until thesame are cooled, thereby rendering such a fuse safe for use in thevicinity of combustible ma terials which might otherwise catch fire andcause damage to the building in which the fuse is used.

Inasmuch as the gases which are produced upon a melting of the fusibleelement serve as conductors of electrical energy, it is important tobreak up this direct line of travel between the two terminals of thefuse between which these electrical charges might travel through themedium of these gases. In the present type of fuse,

this important item of construction has been overlooked, and even thoughthe fusible element has been melted for breaking the circuit, electricalcharges nevertheless may pass between these 56 spaced terminals as bymeans of the burned gases which act as conductors.

It is therefore an object of the present invention to provide a novelfuse wherein suitable means is provided for controlling the pressurebuilt up within the chamber of the fuse for extinguishing.

the arc whereby the body of the fuse is not subjected to burstingpressures.

It is also another object of the present invention to provide a novelfuse in which suitable means is provided for controlling these hot gasesproduced upon a melting of the fusible element, whereby the same areconfined within the fuse until cooled.

Another object within the purview of the present invention is to providea novel fuse of such a construction wherein the various parts are soassociated that electrical charges in the circuit cannot be transferredthrough thegases between the terminals of the fuse when the fusibleelement has melted to break the circuit.

Other objects, features, capabilities and advantages are comprehended bythe invention, as will later appear and as are inherently possessedthereby.

Referring to the drawing:

Figure 1 is a view in cross section of a fuse made in accordance withthe present invention;

Figure 2 is a view in cross section taken in a plane represented by line22 of Figure l of the drawing; 30

Figure 3 is a fragmentary viewin cross section taken in a planesubstantially represented by line 33 of Figure 2 of the drawing; and

Figure 4 is a view in perspective of the cap for the fuse shown inFigures 1 to 3 inclusive.

Referring now more in detail to the drawing, an embodiment selected toillustrate the present in vention is shown as comprising a base or body2 which may have a substantially cylindrical por tion formedwith achamber or cavity' l, and a tapered frusto-conical end part 6 having anopening (not disclosed) through which protrudes a terminal 8 adapted toengage with one end of a fusible element 10. This fusible element 10extends toward the open end of the cylindrical part of the case or body2 and has a central part extending across its opening in the form ofspaced restricted portions 12, the other end of the fusible element 10passing over the edge of the cylindrical part of the body 2 and beingconnected in any desired manner to a screw shell 14 which forms theother terminal for the fuse.

This screw shell 14 may be formed of any suitable material, and has anend formed with an inturned flange or spun portion 16 which is providedwith a plurality of indented portions to provide protuberances 18. Thisscrew shell 14 is provided with external threads adapted to havethreaded engagement with a cap 20 internally threaded as at 22 forreceiving the thread of the screw shell 14. In the present embodiment,the fuse is of the visible type and is provided with an opening 24 inthe cap member 20 which is normally closed by a closure member 26 of anytransparent or translucent material, such as mica or the like, which isadapted to be positioned between the inturned end 16 of the screw shell14 and the apertured wall 23 of the cap member 20, this wall beingformed with the open ing 24 whereby the fusible element 10 may beobserved through this transparent closure member.

As previously indicated, the present invention is primarily concernedwith the idea of controlling the gases formed within the chamber orcompartment 4 when the fusible element 10 melts at the time of a shortcircuit in the line in which the same is provided. This controlling ofthe gases as well as the pressure thereof within the chamber 4necessitates the providing of a suitable control outlet or passage fromthe chamber 4 to the atmosphere. In the present embodiment selected toillustrate the invention, this outlet or passage includes the opening24. As clearly shown in Figure 4 of the drawing, the end wall 28 of thecap member 20 is formed with an inner series of raised portions orprojections '30 between each of which portions is an opening, such asthe opening 32. These'raisedportions or projeetions 30 are preferablyconcentric with the opening 24 and are spaced from a second series ofraised portions or projections 34, between each or" whioh is an opening36. It will be observed that theopenings 32 of the first seriescommunicate with the channel or groove formed by the .wall 28 and themembers of the first and second series, and the same are oppositelydisposed in relation-to the members of the second series. Similarly, theopenings 36 communicate with this channel or passage between the seriesof projectienswand are oppositely disposed in relation to the members ofthe inner series. It will therefore be obvious that the arrangement ofthese series one to the other provides bafiling means for interruptingthe passage of gases through the open n s 36 a d t i te med passa btween the mernbers of the series through the openings 32 through theopening 24 into the atmosphere. The closure member 26 is of a diameterless than the diameter of the threaded opening for the 02p 20, and thesame is held in association with the projections formed on the cap 20,as by means of the screw shell 14, which may bese-rewed into engagementtherewith. The protuberances 18 heretofore referred to engage with theclosure member 26 for maintaining this closure member in spaced relationto the end of the screw-shell 14, whereby gases may pass outwardlyfromthe chamber 4, between these pro tuberances 18, around the edge ofthe closure member 26 and through the tortuous passages providedby theseries of projections 30 and 34.

"In securing the screw shell to the cap, the same may be effected byproviding staking holes or recesses 38in spaced relation in thewall 28of a the cap and staking portions 40-into these staking holes orrecesses, as by means of a staking tool,

th re y preventin th un w h p from the screw shell.

As hereinbefore referred to, the present invention also. contemplatesthe idea of providing a constru'ctionin a fuse in which there is nodanger of the are forming between the terminal 8 and the screw shellwhich acts as another terminal through the medium of the gases ofcombustion formed at the time of melting of the fusible element, whichgases serve as a conductor. This is prevented in the present embodimentas by providing the end of the cylindrical part of the casing or body 2with an annular recess 42 which is adapted to receive the spun orinturned end 16 of the screw shell 14. With this construction, it willbe clearly apparent that when the body member 2 is in the position asshown in Figures 1 and 3 of the drawing, the spun or inturned end 16 ofthe screw shell is separated from the chamber 4 as by means of theshoulder 44 formed by the recess 42. Inasmuch as the screw shell 14 isconnected to one end of the fusible element 10 and serves as a terminalfor this fuse, this shouldered construction for the cylindrical part ofthe case or body 2 prevents any possibility of an arc jumping betweenthe inturned or spun end 16 of this screw shell and the terminal member8 which has a part projecting into the chamber 4 and connected to the,other end of the fusible element 10.

It will also be clearly apparent that the series of projections 30 and34 are so arranged as to act as bailies to provide tortuous passages forthe gases formed in the chamber 4, and it is of course understood thatthe same may be arranged in any desired manner for suitably controllingthese gases to keep the same confined until cooled, as likewise tocontrol the pressure built up within the chamber 4.

In forming this fuse, thebody or casing ,2 is inserted within the screwshell, after the latter has been staked in place within the cap 20 andthe end 46 of the screw shell spun inwardly, as disclosed in Figure 1,to engage with the shoulder 48 adjacent the frusto-conical end 6 formaintaining this body or casing in positiontherein. In order to preventtwistingand turningof the body or casing 2 within the screw shell 14,the shoulder 48 may be formed with staking .holes or recesses 50, andportions 52 of they spun or 111-" turned end 4.6 of the screw shell 14may be pressed therein, as by means of a staking tool.

While I have herein describedand upon the drawing shown an illustrativeembodiment of the invention, it is to be understood that the inventionis not limited thereto but may Comprehend other constructions,arrangements of parts, details and features without departing from thespirit of the invention.

I claim:

1. In an electrical fuse, the combination of a body member having achamber provided with an open end, a fusible element in said chamber, acap associated with said member, said cap having an'apertured end walloppositely disposed in relation to said chamber, a closure memberinterposed between said wall and said body mem her and of materialwhereby said fusible element is visible, said closure member having itsedge in spacedrelation with said cap, and means for positioning saidlast-named member in spaced relaticn with the wall forming the open endof said body member and said cap to provide a passage for gases fromsaid chamber through said opening into the atmosphere.

2. In an electrical fuse, the combination of a body member having achamber provided With an open end, a fusible element in said chamber, acap associated with said member, said cap having an apertured end walloppositely disposed in relation to said chamber, a closure memberinterposed between said wall and said body member and ofmaterial wherebysaid fusible element is visible,

i relation with said cap,

I relation with said cap,

I having a chamber,

said closure member having its edge in spaced relation with said cap,and means for positioning said last-named member in spaced relation withthe wall forming the open end of said body member and said cap toprovide a passage for gases from said chamber through said opening intothe atmosphere, said means including members pros jecting from saidwall.

3. In an electrical fuse, the body member having a chamber open end, afusible element in said chamber, a cap associated with said member, saidcap having an apertured end wall oppositely disposed in relation to saidchamber, a closure member interposed between said wall and said bodymember and of material whereby said fusible element is visible, saidclosure member having its edge in spaced relation with said cap, andmeans for positioning said last-named member in spaced relation with thewall forming the open end of said body member and said cap to provide apassage for gases from said chamber through said opening into theatmosphere, said means including members projecting from said wall andspaced apart radially combination of a provided with an from saidaperture.

4. In an electrical fuse, the combination of a body member having achamber, a fusible element in said chamber, a cap associated with saidmember, said cap having an apertured end wall l oppositely disposed inrelation to said chamber and side walls, a closure member interposedbetween said wall and said body member and of material whereby saidfusible element is visible, said closure member having its edge inspaced and means for positioning said last-named member in spacedrelation with said body member and cap to provide a passage for gasesfrom said chamber through said opening into the atmosphere, said meansincluding a series of spaced members projecting from said wall, and asecond series of spaced members spaced from said first-named series andside walls of said cap and being disposed in opposite relation to theopenings between the members of said I first series.

5. In an electrical fuse, the combination of a body member having achamber, a fusible element in said chamber, a cap associated with saidmember, said cap having an apertured end wall i oppositely disposed inrelation to said chamber and side walls, a closure member interposedbetween said wall and said body member and of material whereby saidfusible element is visible, said closure member having its edge inspaced and means for positioning said last-named member in spacedrelation with said body member and cap to provide a passage for gasesfrom said chamber through said opening into the atmosphere, said meansincluding a series of spaced members projecting from said wall andconcentrically arranged in relation to said aperture, and a secondseries of spaced members spaced from said first-named series andconcentrically arranged therewith in oppositely disposed relation to theopenings between the members of said first series and in spaced relation to said side walls.

6. In an electrical fuse, the combination of a screw shell, a bodymember fitting therein and a fusible element in said chamber, a capmember secured to said screw shell and having an opening oppositelydisposed in relation to said chamber, a closure member for H saidopening and of material whereby said fusible element is visible, saidclosure member having its said body member and cap edge in spacedrelation to said cap member, said shell and cap member having means forpositioning said closure member in spaced relation to said body memberand cap member 'to provide a passage for gases from said chamber throughthe opening into the atmosphere.

'7. In an electrical fuse, the combination of a screw shell, a bodymemberfitting therein and having a chamber, a fusible element in saidchamber, a cap member secured to said screw shell and having an openingoppositely disposed in relation to said chamber, a closure member forsaid opening and of material whereby said fusible element is visible,said closure member having its edge in spaced relation to said capmember, and projections on said shell and cap member for positioningsaid closure member in spaced relation to member to provide a passagefor gases from said chamber through the opening into the atmosphere.

8. In an electrical fuse, the combination of a screw shell, a bodymember fitting therein and having a chamber, a fusible element in saidchamber, a cap member secured to said screw shell, said cap having anapertured end wall oppositely disposed in relation to said chamber, aclosure member for said aperture and of material whereby said fusibleelement is visible, said closure member having its edge in spacedrelation to said cap member, and projections on said shell and wall forpositioning said closure member in spaced relation to said body memberand cap member to provide a passage for gases from said chamber throughthe aperture into the atmosphere.

9. In an electrical fuse, the combination of a screw shell, a bodymember fitting therein and having a chamber, a fusible element in saidchamber, a cap member secured to said screw shell, said cap having anapertured end wall oppositely disposed in relation to said chamber, aclosure member for said aperture and of material whereby said fusibleelement is visible, said closure member having its edge in spacedrelation to said cap member, and projections on said shell and wall forpositioning said closure member in spaced relation to said body memberand cap member to provide a passage for gases from said chamber throughthe aperture into the atmosphere, the projections on said wall being instaggered relation to provide a tortuous passage for said gases.

10. A screw shell for an electrical fuse, comprising a member having anend formed with an inturned flange, said flange having a plurality ofindented portions providing outwardly projecting protuberances.

11. A cap for an electrical fuse, comprising a member having anapertured wall and side wall, and radially spaced members projectingfrom said apertured wall and spaced from said side wall.

12. A cap for an electrical fuse, comprising a member having anapertured wall and side wall, and spaced members projecting from saidaper tured wall and spaced from said side wall, said members being instaggered relation.

13. A cap for an electrical fuse, comprising a member having anapertured wall and side wall, a series of spaced members projecting fromsaid wall and concentrically arranged in relation to said opening, and asecond series of spaced members spaced in relation to said first-namedseries and said. side wall and being oppositely disposed in relation tothe openings between the members of said first-named series.

14. In an electrical fuse, the combination of a screw shell, a bodymember fitting therein and having a chamber formed by a wall, said wallhaving an end provided with a recess spaced from the inside face of saidwall and said chamber, said screw shell having a fiangedisposed in saidrecess, a fusible element in said chamber, a cap member secured to saidscrew shell, said cap having an apertured end wall oppositely disposedin relation to said chamber, a closure member for said aperture and ofmaterial whereby said fusible element is visible, said closure memberhaving its edge in spaced relation to said cap member, means for holdingsaid closure member in spaced relation to said apertured wall and saidscrew shell and the wall of said body member.

15. In an electrical fuse, the combination of a screw shell, a bodymember fitting therein and having a chamber formed by a wall, said wallhaving an end provided with a recess spaced from said chamber, saidscrew shell having a flange disposed in said recess, a fusible elementin said chamber, a cap member secured to said screw shell, said caphaving an apertured end wall oppositely disposed in relation to saidcham ber, a closure member for said aperture and of material wherebysaid fusible element is visible,

said closure member having its edge in spaced relation to said capmember, and projections on said shell and wall for positioning saidclosure member in spaced relation to said body member and cap member toprovide a passage for gases from said chamber through the aperture intothe atmosphere.

16. In an electrical fuse, the combination of a screw shell, a capmember embracing said screw shell and having an end wall formed With anaperture, said end wall having spaced projections and a depressedportion, and a closure member between said screw shell and projections,said screw shell having a portion staked into said depressed portion forsecuring said shell, cap and closure members together and to preventrelative movement.

17. In an electrical fuse, the combination of a screw shell, a capmember embracing said screw shell, a body member fitting within saidscrew shell, said screw shell having flangesembracing said body member,one of said flanges having a portion staked to engage said body portionand the other of said flanges having a portion staked to engage said capmember whereby said members are prevented from turning.

CECIL H. GUNTHORP.

